docs: def enable_collection(f):
      """Call the wrapped function with a HistogramCollection as argument."""
      @wraps(f)
      def new_f(h: AbstractHistogram1D, **kwargs):
          from physt.histogram_collection import HistogramCollection
          if isinstance(h, HistogramCollection):
              return f(h, **kwargs)
          else:
              return f(HistogramCollection(h), **kwargs)
      return new_f